Would using one-step posix_spawn instead of two-step fork–exec enable an image-only FFI solution?

[jeremy-w]

The README says there's a problem where GC and such can occur between the fork and exec calls, when they are made via FFI.

There is a newer (2010-ish) POSIX API that supports one-step process creation: posix_spawn. For rigging up stream redirections (stdin, stdout, etc), it supports passing in a set of file actions to be run before starting the child process.

This might be enough to let you successfully spawn a subprocess using a single FFI call.

[guillep]

We have seen the usage of posix_spawn in OSSubprocess already.

However, the thing are not the file redirections but starting the tty session, that requires some function calls before exec'ing.

If there is a full in-image solution that would be great though

[Rinzwind]

It’s been a few years since this issue was opened, but if you’re still interested you can take a look at PTerm pull request #54 in which the implementation was changed to always use posix_spawn. Previously, posix_spawn was only used as a fallback when PTerm could not compile or load its own function pterm_spawn_tty. An issue due to that change that’s still open however is that the controlling terminal of the new process is no longer set, see PTerm issue #58 for details.